From: Firo Yang <firogm@gmail.com>
Date: Fri, 26 May 2017 14:37:38 +0000 (+0800)
Subject: hdlcdrv: Fix divide by zero in hdlcdrv_ioctl
X-Git-Tag: v3.18.105~70
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0a9936458980e73306980539949a7d700eb700c1;p=thirdparty%2Fkernel%2Fstable.git

hdlcdrv: Fix divide by zero in hdlcdrv_ioctl


[ Upstream commit fb3ce90b7d7761b6f7f28f0ff5c456ef6b5229a1 ]

syszkaller fuzzer triggered a divide by zero, when set calibration
through ioctl().

To fix it, test 'bitrate' if it is negative or 0, just return -EINVAL.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Firo Yang <firogm@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index c67a272450727..69421ac067881 100644
--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -571,6 +571,8 @@ static int hdlcdrv_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	case HDLCDRVCTL_CALIBRATE:
 		if(!capable(CAP_SYS_RAWIO))
 			return -EPERM;
+		if (s->par.bitrate <= 0)
+			return -EINVAL;
 		if (bi.data.calibrate > INT_MAX / s->par.bitrate)
 			return -EINVAL;
 		s->hdlctx.calibrate = bi.data.calibrate * s->par.bitrate / 16;